The aim of the study was searching for explanatory variables of high mortality from coronary heart disease (CHD) observed in Poland, with special regards to lipid risk factors, which were determined in a population of Warsaw Pol-MONICA Project. From the randomly selected cohort of Warsaw population, consisted of 348 men and 351 women, aged 35-64 at baseline, the fasting lipid levels were determined three times in 270 men and 266 women. The first study was performed in 1984 year, second in 1988 and third in 1993. The plasma level of triglycerides (TG), total cholesterol (CH) and HDL cholesterol (HDL), after VLDL and LDL precipitation, were measured by standardized enzymatic methods. LDL cholesterol (LDL) was calculated according to Friedewald's formula. Our laboratory was systematically controlled by WHO Lipid Reference Laboratory in Prague and CDC NHLBI Lipid Standardization Program in Atlanta. After ten years of following up total plasma CH increased significantly by 5% in women (from 5.66 to 5.94 mmol/l i.e. 219 to 230 mg/dl) and did not increase significantly in men (increase by 2%, from 5.63 to 5.75 mmol/l i.e. 218 to 222 mg/dl. LDL fraction increased significantly in both sex groups: by 11% in women (from 3.43 to 3.79 mmol/l i.e. 133 to 147 mg/dl) and by 9% in men (from 3.42 to 3.73 mmol/l i.e. 132 to 144 mg/dl). HDL fraction level changed only within the limits of the accuracy of method. Plasma TG decreased significantly in both sex groups; by 12% in women (from 1.58 to 1.39 mmol/l i.e. 140 to 123 mg/dl) and by 19% in men (from 1.93 to 1.57 mmol/l i.e. 171 to 139 mg/dl). The significant increase in percentage of subjects with elevated atherogenic lipoprotein fraction LDL (LDL >or= 4.1 mmol/l i.e. 160 mg/dl) in both gender groups and prevalence of hypercholestrolemia (CH >or= 6.5 mmol/l i.e. 250 mg/dl) in women only was observed during ten years. Simultaneously the significant decrease in the percentage of subjects with elevated level of triglycerides (TG > or = 2.3 mmol/l i.e. 200 mg/dl) in both gender groups was noticed. The relationship between lipid risk factors and age and relative body mass in all subjects was analyzed. In Polish population the levels of lipids and of atherogenic lipoproteins fractions were very high and during ten years of follow up almost all lipid risk factors, except TG, showed disadventage direction of change.